The status of this project is under rapid development and first stable version is v0.8

JSDebugger is a runtime inspecting tool for you to dig into details of your applications or change application logics dynamically.

You have call any Objective-C method at anytime without manually define JSExport!



Calling Methods

var view = UIView.alloc().init();
var k = NSMutableArray.alloc().init();

You may notice the method name is to some extent different from Objective-C. To illustrate it more precisely, the following two steps are executed underlying before calling an Objective-C method:

  • All colons are converted to underscores.
  • Each part of the Objective-C selector is concatenated into single string.

For Example:

application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

will be converted into following string:

application_didFinishLaunchingWithOptions_(application, launchOptions)

Variadic Arguments

JSDebugger Support Variadic Arguments with NIL termination

For Example:

var array = NSArray.arrayWithObjects_(1, 2, 3);

Or you can define your own method with variadic arguments

In Objective-C, you define a class method + (void)test:(int)first,...NS_REQUIRES_NIL_TERMINATION in ViewController,

then you call it with following codes:

ViewController.test_(1, 2, 3, 5, 7, 9, 8);

Getter & Setter

view.backgroundColor = UIColor.redColor();
var color = view.backgroundColor();
var bounds = view.bounds();

Getter Is Not Supported. Use Method Instead Of Getter!!!

For Example:

view.backgroundColor;   // It's Wrong

view.backgroundColor(); // It's Correct


The running context of JSDebugger is totally the same as an ordinary JavaScript file. You can do whatever your want in JSDebugger as long as it satisfied the requirement of JavaScript:

var z = 5;

var k = [1, 2, 3];

var z = {name:'haha', age:15, data:k};


Excluded from the core functions provided with JSDebugger, we develop plugin mechanism for you to enhance the ability that JSDebugger able to cover.


Choose aims to provide your with the ability to access any objects on heaps. The function will search all instances that match the class name you provided exactly and return all found results as an array.

For Example, suppose you have a class named XXXViewController

var vc = choose(XXXViewController);

Then you will make some operation on it:

var view = vc.view();
view.backgroundColor = UIColor.orangeColor();


We provide you with a mechanism to debug instantly with the help of JSDebugger Playground

It's already integrated into JSDebugger. The usage of it is quite simple, suppose you have a test.js on your Desktop.

Follow steps listed below,

  1. include 'JDLocalFileObserver.h' and declare a reference to it.

    @property (nonatomic, strong) JDLocalFileObserver *fileWatcher;

  2. Init it with path to your test.js and file change callback.

     NSString *jsFilePath = @"PathToDesktop/test.js";
     if ([[NSFileManager defaultManager] fileExistsAtPath: jsFilePath]) {
         self.fileWatcher = [[JDLocalFileObserver alloc] initWithFilePath: jsFilePath changeBlock:^{
             NSLog(@"[JSDebugger]::found test.js change");
             dispatch_async(dispatch_get_main_queue(), ^{
                 [[JDEngine engine] evaluateScriptAtPath: jsFilePath];
         [self.fileWatcher start];
  3. Now, whenever you change something in your test.js and save it(Command + S), your will find JSDebugger automatically reload the content of test.js and start to evaluate it.

  4. Do not forget to stop the local file watch whenever you don't need it

     [self.fileWatch stop]

If you still get confused, just checkout the code in the JSDebuggerDemo.


Checkout demo.js in the JSDebuggerDemo, it shows great detail of what you can do with JSDebugger.


  • JunyiXie


Here we list all features currently supported by JSDebugger:

  • [x] Class Methods
  • [x] Instance Methods
  • [x] Instance Property
  • [x] Custom Setter
  • [x] Playground
  • [x] Data Structes: primitive types, object, class, struct (Partially)
  • [x] Choose
  • [x] Introspect (Partially)
  • [ ] Customized Struct
  • [ ] Getter
  • [x] VA_LIST
  • [x] Associate Object
  • [ ] Block
  • [x] C Pointer

What's Next

An IDE with live Objective-C to JavaScript convertion is under development.
You can really look forward to it!